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Table 1 Characteristics of the selected 3F proteins and their derivative peptides.

From: Directed evolution of a three-finger neurotoxin by using cDNA display yields antagonists as well as agonists of interleukin-6 receptor signaling

No. Name Sequence1 aa2 Disulfide Kd(nM)3 Function4 IC505(nM) IC50/EC506(μM)
1 R10-17 SRPRLN GLAPRAIRAQ TPRARTG 70 - 152 ± 10 NC NC -
2 R10-15 QLLACR ATRHTLGHNL ACETPAS 70 - 115 ± 9 C and NI 102 ± 13 NI
3 R10-13 QLLACR ATRHTLGHNL TPRARTG 70 - 48 ± 8 C and I 113 ± 7 1.4 ± 0.3
4 R10-14 APLPYT ATRHTLGHNL ACETPAS 70 - 55 ± 6 C and A 164 ± 9 0.02 ± 0.006
5 13-L1 LVCYQLLA S R PGTLETG PDDFTCV 24 C3 and C23 ND I ND 10 ± 1.5
6 13-L2 ETCPDDFTGVATRHTLGHNL TQYCS 25 C3 and C24 ND NI ND NI
7 13-L3 ACAIPTPRARTG C 13 C2 and C13 ND NI ND NI
8 14-L1 LVCYAPLPYT PGTLETG PDDFTCV 24 C3 and C23 ND A ND 0.03 ± 0.005
9 14-L3 IPACETPAS C 10 C4 and C10 ND NI ND NI
  1. 1Loop sequences of the proteins are for R10-17, 15, 13 and 14. Sequences of individual peptides are shown in full. 13-L1 represents loop 1 of the protein R10-13, bold letters indicate point mutations, and loop sequences are underlined.
  2. 2The number of residues in the proteins (e.g., 70) includes 61 residues of the protein, spacer GGS and 6xHis.
  3. 3Affinity was measured by Elisa (25). IL-6 was also assayed and the Kd value was found to be 20 ± 5 nM. ND = not determined.
  4. 4NC = Non-Competitive, C = Competitive, NI = Non-Inhibitory, I = Inhibitory, A = Agonist.
  5. 5IC50 was determined by ELISA. IL-6 was also assayed and the value was found to be 80 ± 3 nM.
  6. 6Measured by IL-6 dependent DS-1 proliferation assay. IC50 = concentration for 50% growth inhibition, which for monoclonal antibody was determined to be 1.2 ± 0.15 nM and ED50 = 50% effective concentration, which for IL-6 was found to be 15 ± 2 pM.